How do you change the pictures in the box on the right because some of the chapter covers are wrong?

I'm assuming you mean the chapter covers and know how to edit pages... in which case you go to one of the square thingy-ma-jigs (templates) at the very beginning of the page (it should say template:info box chapters) and click edit (its an edit in an edit 8D)

then under image replace with file you want (file probably has to be on wiki though so if there isn't one you want upload it)
also make sure pic is of sufficiently good quality
and as always consult other on talk page or blog :)